.SETFRAME
Fills in the frame register field and offset in the unwind information using the specified register (reg) and offset (offset). The offset must be a multiple of 16 and less than or equal to 240. This directive also generates a UWOP_SET_FPREG unwind code entry for the specified register using the current prologue offset.
.SETFRAME reg, offset
.SETFRAME allows ml64.exe users to specify how a frame function unwinds, and is only allowed within the prologue, which extends from the PROC FRAME declaration to the .ENDPROLOG directive. These directives do not generate code; they only generate .xdata and .pdata. .SETFRAME should be preceded by instructions that actually implement the actions to be unwound. It is a good practice to wrap both the unwind directives and the code they are meant to unwind in a macro to ensure agreement.
For more information, see MASM for x64 (ml64.exe).
The following sample shows how to use a frame pointer:
; ml64 frmex2.asm /link /entry:frmex2 /SUBSYSTEM:CONSOLE _text SEGMENT frmex2 PROC FRAME push rbp .pushreg rbp sub rsp, 010h .allocstack 010h mov rbp, rsp .setframe rbp, 0 .endprolog ; modify the stack pointer outside of the prologue (similar to alloca) sub rsp, 060h ; we can unwind from the following AV because of the frame pointer mov rax, 0 mov rax, [rax] ; AV! add rsp, 060h add rsp, 010h pop rbp ret frmex2 ENDP _text ENDS END
